The present invention relates to apparatus and methods for controlling electrical energization of one or more signal devices and more particularly to circuits and methods for electrically energizing signal devices in one or more different energization patterns.
Without limiting the scope of intended applications of tile inventive apparatus for producing visual, acoustic, radio and other signals from signal sources in stationary or mobile environments, the background of the invention is described in connection with the field of emergency vehicle warning lights. Warning lights are utilized on many different types of vehicles such as police cars, fire trucks, ambulances, tow trucks, and utility trucks to visually indicate their presence during emergencies. The warning lights may include light sources mounted in a light bar which is installed on the exterior of the vehicle as we]l as head lights and tail lights, for instance.
Prior emergency vehicle warning light control circuits typically produce warning flashes consisting of an ON period followed by an OFF period of little or no intensity. These two periods comprise one cycle and the cycle is repeated continuously. The flash rate of the warning lights may be adjusted. The "flash rate" is defined as the number of ON periods per minute. The flash duration of the ON period for the warning lamps may also be adjusted. A circuit having both an adjustable flash rate and duration is disclosed in U.S. Pat. No. 3,584,257.
The ability of signal apparatus to attract attention and encourage cooperation with authorized personnel is important to the safety of the general public. Signals which are only moderately conspicuous or which diminish in noticeability or psychological conspicuity over a period of years as the public becomes increasingly familiar with them are potentially less effective in preventing injuries and fatalities. Accordingly, in emergency vehicle and other applications it is desirable to provide warning signals that provide a new dimension of noticeability and conspicuity in various emergency and other conditions.